Light cured or photocured resins are well known and are particularly used in the preparation of surface coatings and in the preparation of fiber reinforced composites such as prepregs.
Light cured or photocured putties have found a use in moldings for windows, canopy repair and vehicle repair. However, their applications and use have been limited when they have been applied in thick sections, as a body or filler putty or for general repair. They must be thickened in orders for them to adhere and cure and not run or slough off. Usually the thickening agents are low cost materials such as calcium carbonate or natural mineral. However, such thickeners block or absorb the wavelengths of light necessary for effective curing. When a putty or molding is to have a thickness of at least 20 mm, the thickening agent must be translucent or transparent to visible/UV light and also possess properties which do not interfere with the general characteristics of the mold or putty. The thickener must be such that it does not separate out, and that when the resin is cured, that the cured resin containing the thickener must be light transparent or translucent in the resin system to wavelengths between 350 and 420 mm, be finely divided and have interaction with the uncured resins so that it does not separate out.